/**
 *
 * ArrayStack<E>
 *     void push(E)      O(1)  均摊
 *     E pop()           O(1)  均摊
 *     E peek()          O(1)
 *     int getSize()     O(1)
 *     boolean isEmpty() O(1)
 *
 * @param <E>
 */
public class ArrayStack<E> implements Stack<E>{

    private Array<E> array;

    public ArrayStack(int capacity){
        array = new Array<>(capacity);
    }

    public ArrayStack(){
        array = new Array<>();
    }

    @Override
    public int getSize() {
        return array.getSize();
    }

    @Override
    public boolean isEmpty() {
        return array.isEmpty();
    }

    public int getCapacity(){
        return array.getCapacity();
    }

    @Override
    public void push(E e) {
        array.addLast(e);
    }

    @Override
    public E pop() {
        return array.removeLast();
    }

    @Override
    public E peek() {
        return array.getLast();
    }

    @Override
    public String toString(){
        StringBuilder res = new StringBuilder();
        res.append("Stack: ");
        res.append("[");
        for(int i = 0;i < array.getSize();i++) {
            res.append(array.get(i));
            if(i != array.getSize() - 1)
                res.append(", ");
        }
        res.append("] top");
        return res.toString();
    }

}
